Efficacy of topically delivered moxifloxacin against wound infection by Pseudomonas aeruginosa and methicillin-resistant Staphylococcus aureus.

Wound infection is a common risk for patients with chronic nonhealing wounds, causing high morbidity and mortality. Currently, systemic antibiotic treatment is the therapy of choice, despite often leading to several side effects and the risk of an insufficient tissue penetration due to impaired blood supply. If systemically delivered, moxifloxacin penetrates well into inflammatory blister fluid, muscle, and subcutaneous adipose tissues and might therefore be a possible option for the topical treatment of skin and infected skin wounds. In this study, topical application of moxifloxacin was investigated in comparison to mupirocin, linezolid, and gentamicin using a porcine wound infection and a rat burn infection model. Both animal models were performed either by an inoculation with methicillin-resistant Staphylococcus aureus (MRSA) or Pseudomonas aeruginosa. Wound fluid, tissue, and blood samples were taken, and bacterial counts as well as the moxifloxacin concentration were determined for a 14-day follow-up. A histological comparison of the rat burn wound tissues was performed. Both strains were susceptible to moxifloxacin and gentamicin, whereas mupirocin and linezolid were effective only against MRSA. All antibiotics showed efficient reduction of bacterial counts, and except with MRSA, infected burn wounds reached bacterial counts below 10(5) CFU/g tissue. Additionally, moxifloxacin was observed to promote wound healing as determined by histologic analysis, while no induction of bacterial resistance was observed during the treatment period. The use of topical antibiotics for the treatment of infected wounds confers many benefits. Moxifloxacin is therefore an ideal candidate, due to its broad antibacterial spectrum, its high efficiency, and its potential to promote wound healing.

Modes of action of the new arylguanidine abafungin beyond interference with ergosterol biosynthesis and in vitro activity against medically important fungi.

BACKGROUND: In contrast to the increasing numbers of agents for the treatment of invasive fungal infections, discoveries of new antifungal agents with therapeutic value in dermatomycoses are reported only rarely. METHODS: Abafungin (chemical abstracts service registry No. 129639-79/8) is the first member of a novel class of synthetic antifungal compounds, the arylguanidines. It was first synthesized at Bayer AG, Leverkusen, Germany, and its antifungal action was discovered during the screening of H(2)-receptor antagonists based on the structure of famotidine. To obtain insight into its mode of action and antifungal activity, various tests were carried out with different fungal pathogens in vitro. RESULTS: Abafungin was found to have potent antifungal activity. Furthermore, mode-of-action studies suggested that abafungin exerts its antifungal activity regardless of whether the pathogens are growing or in a resting state. One target of abafungin was found to be the inhibition of transmethylation at the C-24 position of the sterol side chain, catalyzed by the enzyme sterol-C-24-methyltransferase. A second action of abafungin seems to be a direct effect on the fungal cell membrane. CONCLUSION: The observed characteristics of abafungin indicate that abafungin might be a promising antifungal agent defining a new class of antimycotics.

Antimalarial efficacy and drug interactions of the novel semi-synthetic endoperoxide artemisone in vitro and in vivo.

OBJECTIVES: The in vitro and in vivo efficacy and drug-drug interactions of the novel semi-synthetic endoperoxide artemisone with standard antimalarials were investigated in order to provide the basis for the selection of the best partner drug. METHODS: Antimalarial activity and drug interactions were evaluated in vitro against Plasmodium falciparum by the incorporation of [(3)H]hypoxanthine. In vivo efficacy and drug interactions were assessed using the standard 4-day Peters' test. RESULTS: Artemisone was 10 times more potent than artesunate in vitro against a panel of 12 P. falciparum strains, independent of their susceptibility profile to antimalarial drugs, and consistently 4 to 10 times more potent than artesunate in rodent models against drug-susceptible and primaquine- or sulfadoxine/pyrimethamine-resistant Plasmodium berghei lines and chloroquine- or artemisinin-resistant lines of Plasmodium yoelii. Slight antagonistic trends were found between artemisone and chloroquine, amodiaquine, tafenoquine, atovaquone or pyrimethamine and additive to slight synergistic trends with artemisone and mefloquine, lumefantrine or quinine. Various degrees of synergy were observed in vivo between artemisone and mefloquine, chloroquine or clindamycin. CONCLUSIONS: These results confirm the increased efficacy of artemisone over artesunate against multidrug-resistant P. falciparum and provide the basis for the selection of potential partner drugs for future deployment in areas of multidrug-resistant malaria. Artemisone represents an important addition to the repertoire of artemisinin combination therapies currently in use, as it has enhanced antimalarial activity, improved bioavailability and stability over current endoperoxides.

BAY X1005, a new selective inhibitor of leukotriene synthesis: pharmacology and pharmacokinetics.

The enantiomer BAY X1005 [(R)-2-[4-(quinolin-2-yl-methoxy)phenyl]-2-cyclopentyl acetic acid] potently inhibits LTB4 synthesis in isolated PMNL of various species (IC50 mumol/l, human 0.22, rat 0.026, mouse 0.039) and LTC4 synthesis in mouse macrophages (IC50 0.021 mumol/l). Due to high protein binding the in vitro potency for LTB4 synthesis inhibition in whole blood is lowered to 17 mumol/l as determined by RIA. BAY X1005 is selective for the 5-lipoxygenase pathway leaving 12-HETE and HHT unaltered, as determined in human whole blood. After oral application BAY X1005 inhibits edema formation and myeloperoxidase activity in the arachidonate-induced mouse ear inflammation test (ED50 48.7 and 7.9, respectively). Oral activity in the rat ex vivo is found in whole blood for LTB4 synthesis inhibition (ED50 11.8 mg/kg p.o.). BAY X1005 demonstrates a high bioavailability (f 86%) with a Cmax of 13 mg/l and t1/2 of 3.5 h in the rat at 10 mg/kg p.o. Thus, the pharmacodynamic, pharmacokinetic profile and safety aspects of the leukotriene synthesis inhibitor BAY X1005 allow testing in man for its therapeutic potential in inflammatory and allergic diseases.

In vitro pharmacology of BAY X1005, a new inhibitor of leukotriene synthesis.

BAY X1005, (R)-2-[4-(quinolin-2-yl-methoxy)phenyl]-2-cyclopentyl acetic acid, is an enantioselective inhibitor of leukotriene biosynthesis. It effectively inhibits the synthesis of LTB4 in A23187-stimulated leukocytes from rats, mice and humans (IC50 0.026, 0.039 and 0.22 mumol/l, respectively) as well as the formation of LTC4 (IC50 0.021 mumol/l) in mouse peritoneal macrophages stimulated with opsonized zymosan. The compound is, however, less active in inhibiting LTB4 synthesis in human whole blood (IC50 17.0 and 11.6 mumol/l, as measured by RIA or HPLC, respectively). BAY X1005 exhibits a high enantioselectivity in human whole blood (31 times over the (S)-enantiomer). BAY X1005 is shown to be a selective inhibitor of the formation of 5-lipoxygenase-derived metabolites in vitro, without effects on other routes of arachidonic acid metabolism such as 12-lipoxygenase in human whole blood and cyclooxygenase in both mouse macrophages and human whole blood. BAY X1005 is devoid of any antioxidant activity (methemoglobin induction and xanthine-xanthine oxidase assay), without effects on granule release and with only weak effects on reactive oxygen species generation in human PMNL.

Some problems in the structural elucidation of fungal metabolites.

In the structural elucidation of natural products, problems may arise owing to extensive signal overlap and line broadening in the NMR spectra as well as unexpected chemical reactions. This is illustrated in the analysis of some novel compounds isolated from fruit bodies of toadstools and slime moulds, including infractopicrin, lascivol, retipolide A, arcyroxepin A and rubroflavin. In some cases, the problems could be solved by spectroscopic techniques such as two-dimensional INADEQUATE experiments, nuclear Overhauser enhancement measurements or X-ray structural analysis; in other cases, chemical transformations were necessary to resolve the structure.